Kevin Boyle, who has died of cancer aged 67, was an internationally respected human rights lawyer, activist and academic. He had recently become emeritus professor of law at the University of Essex after more than two decades there as one of its leading scholars. From 1990 to 2003 and again in 2006-07, Kevin was director of the university's Human Rights Centre, developing it into a multidisciplinary powerhouse. At the same time, as a practising barrister (he was called to the bars of Northern Ireland, the Irish Republic and England and Wales, and from 1992 was associated with Doughty Street Chambers in London), Kevin brought many human rights cases before the European commission and court of human rights.

The numerous cases against Turkey that he and his Essex colleague Françoise Hampson took on behalf of the Kurdish Human Rights Project concerned the gravest violations: torture, murder and enforced disappearances. In recognition of this work, the two colleagues were named lawyers of the year in 1998, an award made by Liberty and the Law Society Gazette to mark the 50th anniversary of the UN declaration of human rights. Such successful prosecutions became the raw material for scholars and practitioners to trace a fast-evolving field of international human rights law.

They also laid a strong foundation of precedent which helped the European court of human rights to address similar atrocities perpetrated by Russian forces in Chechnya.

Kevin took a year away from teaching when, in 2001, the then UN high commissioner for human rights, Mary Robinson, the former president of Ireland, asked him to join her in Geneva as her senior adviser and speechwriter. His first day in office was 11 September 2001, when, after consulting colleagues around the world, he advised Robinson to denounce the attacks on the World Trade Centre as a crime against humanity, rather than simply a violation of human rights. After his return to Essex, Kevin became chair of Minority Rights Group International, an office he reluctantly had to give up when his health declined.

Kevin was born in Newry, County Down, one of nine children of a Northern Irish Catholic taxi driver, Louis Boyle, and his wife Elizabeth. His upbringing was traditional, strict Catholic: he was educated by the Christian Brothers and served as an altar boy, but when in 1961 he went to study law at Queen's University Belfast, the sectarian outlook gave place to broader humanitarianism.

After graduation in 1965 and a diploma in criminology from Cambridge in 1966, Kevin became a lecturer at Queen's and by 1968 was active in the Northern Ireland civil rights movement. He was a spokesman for the People's Democracy group, formed by students protesting at the repression of civil rights' demonstrations, and later centred his activities on the Northern Ireland Civil Rights Association, of which he became an executive board member.

Together with his colleague and friend Professor Tom Hadden, Kevin spent his time during the Troubles exploring avenues for the peaceful resolution of the conflict, presenting some of their ideas in their book, co-authored with Paddy Hillyard, Law and State: The Case of Northern Ireland (1975).

In 1972 Kevin went to Yale University for a year of intellectual renewal, returning first to Queen's and then in 1978 becoming the first full-time staff member of the law school of University College Galway (now the National University of Ireland, Galway). In 1976 he had married Joan Smyth, a language teacher, and both came to regard their years in Galway, raising their two sons, as a magical time.

There, Kevin founded the Irish Centre for Human Rights in 1980, bringing in new full-time staff and enticing his many friends in the field to visit Galway and share their experience with the students. He also became active in international human rights work, going on several missions for Amnesty International, including a trial observation in the Gambia and a major two-year study of South Africa's pass laws. In this context, observation was sometimes complemented by practical humanitarianism: shocked by the oppressive system and its impact on poor migrant labour, Kevin himself paid the fines of poor women he witnessed on trial in a magistrates court for breaching the pass laws by travelling in search of their husbands.

In 1986 Kevin was appointed founding director of Article 19, the international non-governmental organisation promoting freedom of expression and of the press, which he led to prominence and stability. In this capacity he initiated a high-profile campaign on behalf of Salman Rushdie, whose novel The Satanic Verses had provoked a fatwa from the Iranian leader Ayatollah Khomeini. Kevin formed and chaired a special international committee in 1989 that developed a "world statement" in support of Rushdie with some 12,000 signatures, 2,500 those of writers, many of them famous names in world literature.

That year Kevin became professor of law at the University of Essex, with its already prestigious Human Rights Law Centre established by Professor Malcolm Shaw. None of his high-profile activity on the international stage diminished Kevin's commitment to his students, many of whom now work in institutions concerned with human rights throughout the world, and who hold Kevin in affectionate esteem as teacher and mentor. Approaching retirement brought a spate of honours, but he counted as his most cherished accolade a festschrift with contributions from students and colleagues presented to him in September last year.

He is survived by Joan, sons Mark and Stephen, four brothers and three sisters.

•Christopher Kevin Boyle, legal scholar and barrister, born 23 May 1943; died 25 December 2010